E-ELT - 42 M TELESCOPE

LARGE OBSERVATORY MIRRORS & THE 42 METER E-ELT

FROM WIKIPEDIA:

The European Extremely Large Telescope (E-ELT) will be a
ground-based astronomicalobservatory
with a 42-meter diameter segmented mirror. The design features a filled aperture
mirror with an area of 1,300 m².[1]
On 26 April 2010, the European Southern Observatory
(ESO) Council selected Cerro Armazones, Chile, as
the baseline site for the planned E-ELT.[2]
The telescope's "eye" will be almost half the length of a soccer pitch
in diameter and will gather 15 times more light than the largest optical
telescopes operating today. The telescope has an innovative five-mirror
design that includes advanced adaptive optics to correct for the
turbulent atmosphere, giving exceptional image quality. The main mirror
will be made up from almost 1000 hexagonal segments. If completed it
will become the largest of a new generation of Extremely Large Telescopes.

Although with significantly less area and aperture than the E-ELT,
the 25 m/368 m² Giant Magellan Telescope and 30
m/655 m² TMT are also targeting 2018 for
completion.

Contents:

Goals and Planning

The ESO is focusing on this design after a feasibility study
concluded the proposed 100 metres (330 ft) diameter Overwhelmingly Large Telescope
would cost €1.5 billion (£1 billion), and be too complex. Current
fabrication technology limits single mirrors to being roughly 8 metres
(26 ft) in a single piece. The next-largest telescopes currently in use
are the Gran Telescopio Canarias and Southern African Large
Telescope, which each use hexagonal mirrors fitted together to make a
mirror more than 10 metres (33 ft) across. The E-ELT would need to use a
similar design. In addition, the E-ELT would also need to use
techniques to work around atmospheric distortion of incoming light,
known as adaptive optics (AO).

Project E-ELT has the aim of observing the Universe in greater detail
than even the Hubble Space Telescope. A mirror of approximately
42 metres (138 ft) would allow the study of the atmospheres of extrasolar planets.[citation needed] The
E-ELT is now planned in the Astronet
Infrastructure Roadmap, and “is currently going through a Phase B study
that will end with a Final Design Review of the whole facility in
2009/2010. This Phase B study includes contracts with industry to design
and manufacture prototypes of key elements like the primary mirror
segments, the adaptive fourth mirror or the mechanical structure. It
also includes concept studies for eight instruments.”[3]

Because of the competition with some similar projects (in particular
the Thirty Meter Telescope and the Giant Magellan Telescope), “the
decision for the construction of the European ELT cannot be deferred
later than 2010.”[3]
The construction period is estimated to be 7–8 years leading to first
light around 2018. The design phase of the 5-mirror anastigmat
(€57M) is fully funded within the ESO budget, and the construction cost
is estimated to be €960M (including first generation instruments).
“About €350M for the construction phase are available within the
existing budget integrated over a period of ten years. One of the goals
of the preparatory phase is to study the possibilities for additional
funding. Additional activities on the organisation of the project and
the mission design are supported through a €5M FP7 grant.”[3]

Telescope at work, with its dome open and its record-setting 42-metre
primary mirror pointed to the sky.

Instrumentation

Model of the gigantic and intricate structure inside the enclosure of
the E-ELT.

Eight different instrument concepts and two post-focal AO modules are
currently being studied, with the aim that two to three will be ready
for first light, with the others
becoming available at various points over the following decade.[4]
The instruments being studied are: